Steven Weinberg: What’s the matter with quantum mechanics?

In this public lecture Weinberg explains the problems with the two predominant interpretations of quantum mechanics, which he refers to as Instrumentalist (e.g., Copenhagen) and Realist (e.g., Many Worlds). The term “interpretation” may be misleading because what is ultimately at stake is the nature of physical reality. Both interpretations have serious problems, but the problem …

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Are quanta particles or waves?

Are quanta particles or waves? The title of this post is an age-old question isn’t it? Particle or wave? Wave or particle? Many have rightly argued that the so-called “wave-particle duality” is at the very heart of quantum weirdness, and hence, of all of quantum mechanics. Einstein said it. Bohr said it. Feynman said it. …

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Gell-Mann on quantum foundations

Google knows enough about me that my YouTube feed now routinely suggests content of real interest. A creepy but positive development ;-) Today YouTube suggested this video of Murray Gell-Mann talking about Everett, decoherence, and quantum mechanics. I had seen this video on another web site years ago and blogged about it (post reproduced below), …

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EPR and Bell for pedestrians

My old friend Mark Alford (WUSTL) was on campus last week for the inaugural meeting of the FRIB-TA (Facility for Rare Ion Beams Theory Alliance). Over beers he told me he had come up with a pedagogical way to explain Bell’s inequality in a single picture. Here it is. Ghostly action at a distance: a …

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Schwinger meets Rabi

Seventeen year old Julian Schwinger meets Columbia professor I. I. Rabi (Nobel Prize 1944) and explains the EPR paper to him. Climbing the Mountain: The Scientific Biography of Julian Schwinger [p.22-23] … Rabi appeared; he invited Motz into his office to discuss ‘a certain paper by Einstein in the Physical Review’! Motz introduced Julian and …

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Instability of Quantum de Sitter Spacetime

New paper! We show that quantum effects (in particular, the horizon temperature originally discovered by Gibbons and Hawking) modify the geometry of de Sitter spacetime. Instability of Quantum de Sitter Spacetime (http://arxiv.org/abs/1501.00708) Chiu Man Ho, Stephen D. H. Hsu Quantized fields (e.g., the graviton itself) in de Sitter (dS) spacetime lead to particle production: specifically, …

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Quantum GDP

  “It’s been only half jokingly said that today a third of GDP is attributable to quantum mechanics,” — former Lockheed CEO Norm Augustine. I’ve heard the one third or 30% of GDP figure from time to time, but have never seen a detailed analysis. A list of modern technologies that arose from quantum mechanics …

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Patterns on the sky

I’m busy reviewing ~200 promotion and tenure cases for my day job, so I don’t have much time to post about the BICEP2 observation of primordial gravitational waves via their effect on the polarization of the cosmic microwave background (CMB). Instead, I refer you to Sean Carroll, Lubos Motl and Liam McAllister (guest poster at …

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